Relief mechanism for fuel pumps



Patented Apr. 6, 1926. I UNITED STATES PATENT OFFICE;

PHILIP LANE SCOTT, OF SYRACUSE NEW YORK, ASSIGNOR TO SUPER-DIESELTRACTOR CORPORATION, OF LA PORTE, INDIANA, 'A CORPORATION OF NEW YORK. I

' RELIEF MECHANISM FOR FUEL PUMPS.

Application filed June18, 1918. Serial No. 240,707.

. To all whom it may concern: vention will appear more clearly from adesame.

Be it known that I, PHILIP LANE Soorr, scription of certainpreferredembodiments a citizen of the United States, residing at thereof as shownin the accompanying draw- Syracuse, in the county of Onondaga and ingsin'which Figure 1 represents, chiefly State of New York, have inventedcertain in section, a fuel pump provided with one 60 new anzl usefulImprovements in Relief form of relief valve; Fig. 2 is a portionMechanism for Fuel Pumps; and I do herof the fuel pump of Fig. 1 showinga modiby declare'the following to be a full, clear, tied form of reliefmechanism, and Fig. 3 and exact description of the invention, such 18 asectional view ofa somewhat different as will enable others skilled inthe art to arrangement of the elements of the pump 55 which itappertains to make and 'usethe and a-diiferent form of relief valve.

J ;Referring tothe drawings-and particu- This invention relates toimprovements in larly Fig. 1, the body of the pump is pumps adaptedparticularly for injecting provided with recesses on oppositesidesto liid f l at high pressure into the workrece1ve the usual valves. Thesuction valve ing cylinder of an internal combustion enthrough whlchfuel is drawn into th u p gine, where the fuel is vaporized and thencomprises a plug 11 having a valve seat at ignited by the hightemperature of a charge 12, and belng held 1n place by an outer plug ofair which has previously been admitted 13 which is threaded as at 14 forattachto the cylinder and compressed to a high ment to a pipe leading tothe source of fuel 75 degree during the compression stroke of thesupply. A W sh r 15 e ween the W0 plugs engine. The liquid fuel isordinarily supmsures a tlght joint. The valve 16 is li d th h a Sprayvalve, d ith th normally held against the seat 12 by a spring provide apump usual types of pumps at present in use, th 17 hearing against ashoulder in the inside rate of injection of the fuel decreasesrapidffllc pump casing. 1y toward, the end of the pump stroke, and Thedischarge valve 18 through which the amount of fuel delivered-is then sosmall fuel 1s supplied to the cylinder is held that there is a tendencyfor drops to form against lts seat by a spring 19, the upper i th f lSpray d t th in f th end of which bears against aplug 20 screwed sprayvalve i t th b ti h mb into the side of the pump casing, and threadf thh d ed as at 21 for attachment. to a pipe lead- It is an object of thepresent invention to ug o the combustion chamber of. the ensystem h imeans f "me. A washer 22 prevents any leakage suddenly relieving thepressure before .too gh t e threads of the plug 20. 00

l t f pumping i r ch d, that Between the two valves is the pump chamthespray valve shall quickly close and out, ber'23 Within which a plunger24 is adaptoii any dripping of fuel that might otherd to pr te. Theplunger 24 passes i occur t d th d f th p through a bore 1n the'pumpcasing 10, "and at its outer end carries a roller 25 pressed stroke. 1

In accordance with the present invenagainst aitcam 26 by a Spring 27.The cam ti th i id d on th hi h pree- 26 1s mounted on a shaft 28 whichis actusure side of the fuel pump, a relief valve flie om the movingparts of the engine or equivalent ve' nt controlled byand achroughsuitable gearing.

'tuated in timed relation to the other mov- The construction thus fardescribed is one ing'parts of the pump, so that as the pump of the usualforms of pumps adapted to plunger eh th df its king supply liquid .fuelat high pressure to the,

stroke the valve will be quickly opened to cylinder of an internalcombustion engine, cause a sudden decrease in the pressure of but n 7 ni the p n invention the oil in the passage leading to the spray there sprovided on the hi'ghpressure side 05 valve, with the result that thelatter will 9f the pump, a relief valve which in Fig. 1 1 be quicklyclosed and, the supply of fuel is shown as avalve stem 30 slidablymountto the combustion chamber of the engine ined in a borein the pumpcasing, and 'prostantly cut off to prevent any excess-fuel VldBd with apomted mner end which fits from dripping through the spray valve. withina conical passageway between the no The particular nature of the pres ntinbore'and the ch ber of the discharge valve 18. The valve stem isslotted as at 31 to permit the passage of liquid through the reliefvalve. The outer end of the valve stem 30 is provided with a shoulder 32fitting within a cavity in the pump casing. A spring'33 engages theshoulder 32, and at its other end bears against a block 34 which isslidably mounted in the bore, but prevented from turning therein by ascrew 35 having its inner end fitted within a slot on the side of theblock. The outer end of the slidable block is engaged by a cam 36 on ashaft 37 which by means of gears 38, 39 and 40 is driven by and in timedrelation with the shaft 28, carrying the cam 26 which controls theoperation of the pumping plunger 24 In the operation of the mechanismdescribed above, the plunger 24 is operated to draw liquid fuel, throughthe suction valve 16 on the outward stroke of the plunger, and force itthrouglr'the discharge valve 18 on the inward stroke of the plunger, itbeing understood that ,the cam 26 is driven in timed relation from themoving parts of the engine to cause the working stroke of the plunger tobe performed at the right instant to force the fuel through a sprayvalve into the combustion chamber of the engine. I The shaft 37 carryingthe cam 36 which controls the slidable block 34 is 'so driven with relation to the cam 26 that as the plunger 24 approaches the end of itspumping stroke, the nose of cam 36 will pass 0d of the end of block 34and thus relieve the force exerted upon the spring 33 so that the forceof the latter upon val e stem 30 will not be suf- .ficient to hold thelatter against the pressure that exists in the discharge chamber at thistime. The relief valve will thus open and relieve the pressure on thedischarge side of the pump. In connectiom with a pump of the characterdescribed, there is at the cylinder, a spray valve through which liquidfuel is injected into the combustion chamber, and the release ofpressure between this valve and the discharge valve 18 will cause thespray valve to be quickly closed, cutting 011 any dripping of fuel intothe cylinder. The relief valve 30 will remain open until the nose of cam36 again engages the end of sliding block 34 to again putthe spring 33under compression suflicient to hold the relief valve closed against thepressure produced i the chamber of the discharge valve 18 0 next workingstroke of the pump plunger. A fuel supply puinpof the general type shownin Fig. 1. may be operated without the discharge valve 18, the spraywhich controls the admission of fuel into the combustion chamber beingused as an equivalent of the discharge valve. In this case the r liefvalve may be located atany point beyond the suction valve 16, because itis-then only necessary to relieve the pressure in the systhe.

tem between the suction valve 16 and the spray valve to cause the latterto close quickly to prevent leakage into the combustion chamber. a

Figure 2 shows a modification of the invention in which a plunger 45 issubstituted for the valve stem 30 of Figure 1. The plunger 45 isslidably mounted in a bore in the pump casing, but has an oil-tight fit.therein. The outer end of this plunger is its pumping stroke, thenose'of cam 47 passes out of engagement with the head 46, thuspermitting the fluid pressure acting upon the inner end of plunger 45 toforce the latter outwardly against the compression of spring 50, itbeing understood that this spring is so adjusted that it will yieldunder-the pressure existing on the discharge side of the pump, as thepump plunger approaches the limit of its pumping stroke.

Outward motion of plunger 45 will tend to create a vacuum on thedischarge side of the pump, which will cause a sudden decrease ofpressure in the liquid on this side of the pump, with the result thatthe spray valve will be closed quickly to prevent any leakagetherethrough.

If the plunger shown in Fig. 2 is used instead of the valve 30 of Fig.1, it is necessary that the discharge valve 18 be eliminated, or if itis retained, means should be provided for holding it open at thebeginning of the suction stroke of the pump plunger. If the dischargevalve should be left in the pump, the plunger 45, as it is returned toits original p sition by cam 47, would in itself act as a pump and tendto force liquid through the spray valve. If the discharge valve 18 isremoved, then the pump chamber 23 and the chamber with which the plunger45 is associated, are in ated directly-with the pump chamber instead ofwith a chamber communicating wit lthe latter as 1H the case of Figs. 1and 2. in Fig. 3 the pump plunger, the inlet valve and the dischargevalve are substantially the same as the corresponding parts of Ifig. 1,except that the pump plunger 24 has a tapered end as at 55, and the stemof the discharge valve 18' is provided with a ,screw 56 adapted to beengaged by the plunger 24' as the latter approaches the end of thepumping stroke. In this figure, the relief mechanism comprises avalve-stem 57 slidably mounted in a tubular member 58 inserted in a borein the pump casing and communicating with the pump chamber'23. The innerend of the valve stem is tapered to fit a correspondingly formed valveseat at the inner end of the tubular member 58. This tubular member isheld in place against avwasher, 59 by a plug 60 provided with a bore toreceive the enlarged .end 61 of the valve stem, and a spring 62 whic1bears against this enlarged end, and at its other end is held in placeby an adjustable plug 63. The valve stem 57 is provided with one or morelongitudinal -,grooves 6 1 to permit the discharge of liquid from thepump chamber-When the valve stem is forced outwardly by engagement ofthe pump plunger 245 with a screw 65 adjustably mounted in the inner endof valve stem 57.

The force of the spring 62 is such that it holds the valve 57 upon itsseat at the inner end of the tubular member 58 against the pressure thatexists during the pumping stroke, but when the pump plunger 24:approaches the end (if this stroke, it engages the screw 65 and forcesthe valve stem 57 outwardly against the-efl'ect of spring 62, thuscausing the pressure in the pump chamber to be instantly relievedi Atthe same time that the inner end of the pump plunger engages the screw65, the cylindrical part of the plunger will pass under the screw 56 ofthe discharge valve 18' and hold this valve open while the pressure isbeing relieved by the opening of the ,relief valve. Were it not for thisarrangement, the discharge valve 18 would close as soon as the pressurein the pump chamber was relieved, and leakage of liquid might not beavoided; As soon as the pump plunger begins its suction stroke, it movesout ofengagement with the screws 56 and 65, thus permitting thedischarge valve and i the relief valve to close.

I claim:

1. In a fuel injecting system for internal combustion engines having apump supplying liquid fuel under high pressure to an injection valve toopen the valve and force the fuel into the combustion chamber, thecombination of a vent between the pump and the injection valve, meansfor closing said vent during the injection stroke of the pump, and meansfor releasing said closing means near the end of the injection stroke topermit said vent to be opened to abruptly combination of a vent betweenthrough the spray valve the opening into the combustion chamber andcause a sudden closing of the injection valve to prevent dripping of thefuel.

2. In a fuel injecting system for internal combustion engines having apump supplying liquid "fuel under high pressure to an injection valve toopen the valve and force the fuel into the combustion chamber, the thepump and the injectionvalve, a closure for said vent, means for holdingsaid closure in vent-closing position during substantially the entireand means for injection stroke of the pump, releasing said holding meansnear the end of the injection stroke to permit said closure to open thevent to abruptly diminish the pressureof the liquid fuel'at the openinginto the combustion chamber and cause a sudden closing of the injectionvalve to prevent dripping of the fuel.

3. In a fuel injecting system for internal combustion engines having apump supplying liquid fuel under high pressure to an injection valve toopen the valve and force the fuel into and said injection valve, saidvent, means for holding said closing means in vent closing positionagainst the pressure of the fluid between said pum and said injectionvalve during 'substantialiy' the entire injection stroke of the pump,and means for releasing said holding means to permit the pressure of thefluid to open the vent near the end of the injection stroke to cause anabrupt diminution'vof pressure at the opening into the combustionchamber and produce a sudden closing of the injection valveto preventdripping of the" fuel.

4. In a fuel injecting system for internal the combustion chamber, the.combination of a vent between said pump means for closing combustionengines having a pump supply ing liquid fuel under high pressure to aninjectionvalve to open the valve and force the fuel into the combustionchamber, the combination of a vent on the high pressure side of thepump, means for closing said vent against the fluid pressure produced bysaid pump, during its injection stroke, and means under the control ofsaid pump for actuatingrsaid vent closing means to open the vent nearthe end of the injection stroke of said pump to abruptly diminish thepressure of the liquid fuel at the opening into the combustion chamberand cause a sudden closing of the injection valve to prevent dripping ofthe fue j 5. In a fuel injecting system for internal combustion engineshaving a pump supplying liquid fuel under high pressure to an injectionvalve to open thevalve and force the fuel into the combustion chamber,the combination of a vent on the high pressure side of the pump, ventagainst the fluid pressure produced by said pump during its injectionstroke, and means adjustably associated with said closing means andadapted to be engaged by the plunger of the pump for actuating said ventclosin means as the plunger approaches the end 0 its injection stroke toabruptly diminish the pressure f the liquid fuel at the opening into theco bustion chamber and of the engine,' the combination of a ventcommunicating with the conduit, means for closing the vent during theinjection stroke of the pump, and means for releasing the closing meansnear the end of the injection stroke to ermit said vent to be open toabruptly dlminish the pressure of the fuel in the conduit! to cause asudden closing of the injection valve to prevent dripping of the fuel.

7 In a fuel injection system for internal combustion engines, havin apump supplying liquid fuel under hig pressure to an injection valve toopen the valve and force the fuel into the combustion chamber, the

combination of a vent on the high pressure side of the pump, a closurefor said vent a spring for holdin said closure in ventclosing positionagainst the fluid pressure produced by the pump during its injectionstroke, and means operable in timed relation with ,thepump for relievingthe tension of the spring near the end of themjection stroke of the pumpto permit the pressure of the fuel to'act upon the closure to open thevent to cause an abrupt diminution of pressure at the opening into thecombustion chamber and produce a sudden closing of 'the injection valveto prevent dripping of the fuel.

In testimony whereof I affix my sign".

ture.

PHILIP LANE SCOTT

